In recent years, there have been many advances in endoscopic and laparoscopic surgical procedures. In these procedures, a surgeon makes an incision at the desired location where the surgical procedure is to be performed. Typically, a trocar is then inserted into the incision made by the surgeon. By applying pressure against the proximal end of the trocar, the obturator is forced through the tissue until it enters a target location, such as the abdominal cavity or any other desired hollow viscus of the body. The cannula is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the cannula as an accessway to the abdominal cavity. If desired, a pressurizing gas such as, for example, carbon dioxide can be pumped through the cannula of the trocar to inflate the abdomen or hollow viscus of the body. Then, any number of surgical instruments such as, for example, a tissue fastening instrument can be inserted through the cannula of the trocar to perform the surgical procedure.
One such tissue fastening instrument inserted through the cannula during a surgical procedure is the surgical stapler. Surgical staplers are employed by the surgeon during the procedure to sequentially or simultaneously apply one or more surgical fasteners such as, for example, staples or two-part fasteners to body tissue for the purpose of joining segments of body tissue together. An example of a surgical stapler is disclosed in U.S. Pat. No. 5,725,554 issued to Simon et al. A surgical stapler and staple is described for joining together tissue of a patient. The surgical stapler has a long endoscopic arm, a stapling actuation mechanism located at the end of the endoscopic arm, and a handle with a trigger. The staple, which is a rounded M-shape, has a circular cross-section with a flat surface on the lower side. The operation of the trigger causes a linear force to travel through the length of the arm to the stapling actuation mechanism, which forms the staple to fasten tissue. One drawback of the design of this surgical stapler and staple is that the long endoscopic arm has a large cross-section, which requires a larger access port and larger incision to reach the surgical site.
Another such tissue fastening instrument inserted through the cannula during a surgical procedure is the clip applier. Clip appliers are employed by the surgeon during the procedure to sequentially or simultaneously apply one or more clips to body tissue for the purpose of pinching vessels. An example of a clip applier is disclosed in U.S. Pat. No. 5,843,097 issued to Mayenberger et al. A surgical applicator for U-shaped clips is described comprising a handle, a tubular shaft adjoining the handle, a forceps-type applicator tool at the free end of the tubular shaft, a clip magazine in the tubular shaft, a closing mechanism comprising jaws at the distal end of the tubular shaft, and an advancing mechanism arranged in the tubular shaft. The advancing mechanism pushes a clip into the jaws of the closing mechanism. When the handle is actuated, the jaws of the closing mechanism pinch the clip around the vessel. One drawback of the design of this surgical applicator and its U-shaped clip is that the tubular shaft has a large cross-section, which requires a larger access port and larger incision to reach the surgical site.
In minimally invasive surgery, in particular, endoscopic or laparoscopic surgery, it has become desirable to provide smaller instruments capable of reaching surgical sites through smaller access ports, yet still providing the ability to deliver relatively large staples and clips therethrough. Smaller incisions cause less damage in accessing the surgical site and the access wounds from such incisions heal faster. The presently known surgical fastening devices such as, for example, clip appliers and surgical staplers all exhibit the drawback of having an instrument shaft with a large cross-section, which is dictated, in general, by the size of the fastener as it is passed therethrough. Having an instrument shaft with a large cross-section requires a larger access port and a larger incision. Therefore, what is needed is a tissue fastening instrument and tissue fastener having a shaft with a reduced cross-section capable of reaching surgical sites through smaller access ports and smaller incisions.